1. Field of the Invention
The present invention relates to a data communication apparatus that performs communication via a network, a control method thereof, and a computer readable storage medium.
2. Description of the Related Art
As a data communication apparatus that performs communication via a network, there has conventionally been known a printing apparatus that performs printing based on print data received via the network. Such a printing apparatus may have a power saving mode for reducing or stopping power supply to a printing unit or a display unit in order to reduce power consumption when no print data is received or the printing apparatus is not operated for a predetermined period of time.
In addition to the above power saving method, there is a method for reducing a processing load applied on network communication by setting a speed of communication performed via the network at low, thereby reducing power consumption (as discussed in Japanese Patent Application Laid-Open No. 2004-64335).
As a form of network establishment, there is known a spanning tree defined by the Institute of Electrical and Electronics Engineers, IEEE802.1d. As illustrated in FIG. 4, the spanning tree is used by connecting a plurality of bridges (Local Area Network (LAN) switches) between a router 4001 and a terminal (printer or personal computer (PC)). Even when one of the bridges becomes unusable due to a failure or the like, communication to the router is protected from being disabled by dynamically rewriting a routing table of the other bridges (recalculating path information). In other words, when a bridge 4003 becomes unusable, for example, abridge 4006 changes a path to the router from a path via the bridge 4003 to a path via a bridge 4005 and a bridge 4002.
In the spanning tree, when a routing table of each bridge is to be rewritten, the bridges sequentially rewrite the routing table by using a timer. During this period (until all the bridges complete rewriting of the routing tables), no communication can be performed in a sub-network including each bridge.
Thus, in the spanning tree, when a communication speed is dynamically changed as discussed in Japanese Patent Application Laid-Open No. 2004-64335, the routing tables of the bridges are to be rewritten, and hence a period may be generated in which no communication can be frequently performed via the network. As a result, a plurality of terminals in the network is even affected.